1. Field of the Invention
The present invention relates to the structure of a phase-locked semiconductor laser of same phases and high optical output.
2. Description of the Prior Art
In case of rendering the optical output of a semiconductor laser high, it is indispensable from the standpoint of practical use that a laser beam has optical properties permitting condensing or collimation to the diffraction limitation.
In a semiconductor laser device having the ordinary double-heterostructure, it has been proposed to increase the optical output of the whole device by juxtaposing a plurality of emission portions of strips. The proposal is described in, for example, the literature of Appl. Phys. Lett. 34(2), Jan. 15, 1979, pp. 162-165. In actuality, however, the modes, wavelengths and phases of laser beams become different in the respective strips, and there has not been obtained a laser beam of high quality which is applicable to optical communication, an optical disk memory, a laser printer or the like.